Constipation can be defined as an abnormal accumulation of feces resulting in difficult bowel movements. This may result in reduced frequency or absence of defecation. The feces are retained in the large intestine or colon. Since one of the major functions of the colon is water absorption, the retained feces become hard and dry, which makes passing the feces even more difficult. Constipated cats strain in an attempt to defecate resulting in abdominal pain. Some constipated cats may pass small amounts of liquid feces or blood as a result of excessive straining.

What causes constipation?

Factors associated with the development of constipation include:

Hairballs, especially in long-haired cats.

Ingestion of foreign bodies.

Pelvic injuries resulting in a narrowed pelvic canal.

In some cases, there is no obvious cause identified.

Constipation is a condition seen most commonly in middle-aged and older cats.

What is megacolon?

Megacolon is a term referring to a dilated and weak colon that causes severe constipation. Megacolon may be seen as a primary entity or following long-term constipation. When the colon becomes distended with fecal material over a prolonged period of time, its ability to contract may be reduced or lost resulting in megacolon. Feces then accumulates in this abnormally distended and enlarged colon.

How are constipation and megacolon diagnosed?

In most cases, a diagnosis of constipation can be made on the basis of the cat’s clinical signs and medical history. Affected cats usually strain unsuccessfully to defecate and may cry in pain. Any feces passed are hard and dry. The cat may also show signs of lethargy, reluctance to eat, abdominal pain and distention, and vomiting.

Further tests may be needed in order to diagnose the cause of the constipation and these may include abdominal and pelvic x-rays to look for pelvic injuries, colonic strictures or tumors. X-rays are also the primary test for the diagnosis of megacolon.

How can constipation and megacolon be treated?

Treatment varies depending on the cause of constipation. If an obstruction such as a colonic tumor is present, surgical treatment may be performed.

Initial treatment of a cat with constipation may involve administration of enemas and manual extraction of feces by a veterinarian. Removal of feces often requires an anesthetic or sedative. Treatment of dehydration with intravenous fluids may also be needed in cats that have become dehydrated due to decreased appetite and water consumption. If the constipation recurs or becomes a long-term problem, continuous therapy may be needed to prevent recurrence. A wide variety of treatments are available to soften the feces and promote regular bowel movements. High fiber diets may be helpful and lubricating laxatives or stool softeners may also be used in mildly affected cats. Those more severely affected may need drugs that stimulate contraction of the colon. The doses of all of these drugs may need to be altered to produce the desired effect. Ideally, cats should defecate at least once every other day. Over a period of time, resistance to the treatment may be found necessitating an increase in the drug dosage or a change in therapy. No changes to the treatment protocol should be made without consulting your veterinarian.

In long-haired cats, regular grooming and hairball removal agents and diets may reduce hair ingestion and the likelihood of hairballs causing constipation.

It is important to ensure that there is always access to a clean litter tray so that frequent defecation is encouraged.

If megacolon develops or if the constipation is severe and medical treatment is unsuccessful, surgery may be recommended. Surgical treatment involves removal of most of the colon called a partial or sub-total colectomy. Most cats do very well with few side effects following this surgery.

What is the long-term outlook for a cat with this problem?

The long-term outlook varies according to the cause of the constipation; however, most cats can be adequately managed without surgery and resume normal, healthy lives. For cats that require surgery to correct megacolon, the prognosis is good.